JP2010190500A - Carbide combustion device and method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pulverized carbide combustion device and a method therefor, suppressing slugging and generation of NOx. <P>SOLUTION: In this pulverized carbide combustion device provided with a burner for jetting and burning the pulverized carbide and the air at a furnace inlet section, the furnace includes the vertical cylindrical shape, the burner is disposed on a furnace ceiling section so that the pulverized carbide and the air are jetted vertically downward and burned, and further a first swirl flow forming means positioned at a burner downstream side for blowing the air and a low oxygen gas into the furnace and forming the swirl flow in which the low oxygen gas is positioned at the outer periphery, in a face orthogonal to the flow of the combustion gas, and a second swirl flow forming means positioned at a downstream side of the first swirl flow forming means for forming the swirl flow in a face orthogonal to the flow of the combustion gas by blowing the low oxygen gas into the furnace, are disposed along the combustion gas flow in the furnace. An area of the swirl flow formed by the first swirl flow forming means is larger than an area of the swirl flow of the low oxygen gas formed by the second swirl flow forming means. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a combustion apparatus for burning fine carbide and a method thereof, and suppresses slugging caused by ash melting and adhering to the inner wall of a furnace when burning fine carbide, and reducing fly ash adhesion to the furnace inner wall. In addition, the present invention relates to a pulverized carbide combustion apparatus and a method thereof capable of suppressing generation of NOx.

  Conventionally, in an industrial thermal power generation facility, a boiler that generates high-temperature and high-pressure steam by burning solid fuel such as pulverized coal has been used, and the turbine is driven by the steam generated by the boiler. Electricity is generated by a connected generator. As described above, the boiler used in the power generation facility is required to reduce NOx in the exhaust gas from the viewpoint of environmental protection.

  Therefore, as a method for reducing NOx in exhaust gas and improving combustion efficiency, a fuel combustion burner for supplying fuel and air to a boiler, and an air supply port for supplying air to the downstream side of the fuel combustion burner are provided. A so-called two-stage combustion system is known in which the air supplied from the fuel combustion burner is set to an air amount smaller than the amount of air necessary for complete combustion of the fuel, and the remaining air is supplied from the air supply port. By using the two-stage combustion method, it is possible to form a reducing atmosphere and suppress the generation of NOx.

On the other hand, in the two-stage combustion method, when coal or carbide is used as the fuel and the combustion temperature is high, the ash content in the fuel melts and ash adheres to the inner wall surface of the furnace, that is, there is a high possibility that slagging occurs. .
For this reason, Patent Document 1 discloses a technique for preventing slagging by introducing air into a position where slagging is likely to occur and lowering the gas temperature below the ash melting point.
Patent Document 2 has a pulverized coal combustion furnace having four walls, each having nozzles arranged at four corners of the furnace, and through these nozzles, pulverized coal and primary air are fed to the central part of the furnace. A first set of nozzle devices that are introduced so as to be directed tangentially to a first horizontal virtual circle, and nozzles respectively disposed at four corners of the furnace, through which recirculated gas A second set of nozzle devices that are directed into the furnace so as to be directed tangentially to a second virtual circle that concentrically surrounds the first virtual circle, and four corners of the furnace Each part has a nozzle located so that the secondary air can be directed tangentially to the third virtual circle concentrically surrounding the second virtual circle through these slurs. The pulverized coal combustion furnace to be introduced into the furnace is opened. It is.

JP 2002-349846 A JP 59-42202 A

However, the technique disclosed in Patent Document 1 aims to reduce slagging by reducing the gas temperature by introducing air to a position where slagging is likely to occur, that is, a position where the gas temperature is high. The position is the combustion zone where the fine carbide is burned. Therefore, depending on the supply location, the temperature of the combustion zone decreases, unburned is generated, and fine carbides cannot be burned sufficiently. Furthermore, since the entire furnace of the boiler is composed of boiler walls, such a furnace structure does not allow a large fuel supply turn-down, the outlet gas temperature decreases during low-load operation, and operation with a large load change is possible. Have difficulty.
Further, in the technique disclosed in Patent Document 2, since a square furnace is adopted, the swirling flow is disturbed, the swirling flow and the inner wall of the furnace are separated to form a stagnation portion, and fly ash is generated in the stagnation portion. It may be stagnant and it is not sufficient as a countermeasure against slagging. In addition, the primary air outlet and the pulverized carbide outlet need to be oriented in the horizontal direction, and the high-temperature flame may locally significantly damage the facing furnace wall.

  Therefore, in view of the problems of the prior art, the present invention has a furnace wall as a refractory structure, and the outlet gas temperature does not decrease even during low load operation. Therefore, operation with a large load change is possible, and primary air and An object of the present invention is to provide a pulverized carbide combustion apparatus capable of preventing local damage to a furnace wall by jetting pulverized coal vertically downward into a furnace, and further suppressing generation of slagging and NOx, and a method thereof. To do.

  In order to solve the above problems, in the present invention, a furnace having a combustion region for burning fine carbide, and a burner for injecting and burning fine carbide and air into the furnace, the burner at the furnace inlet. In the provided fine carbide combustion apparatus, the furnace has a vertical cylindrical shape, the burner is provided on the ceiling of the furnace, and the fine powder carbide and air are arranged to be blown vertically downward and burned, and the furnace Along the combustion gas flow, air and low oxygen gas are blown into the furnace downstream of the burner to form a swirl flow in which the low oxygen gas is located on the outer periphery in a plane orthogonal to the flow of the combustion gas. And a second swirl flow forming means for forming a swirl flow in a plane perpendicular to the flow of the combustion gas by blowing low oxygen gas into the furnace downstream of the first swirl flow forming means. Provided, the swirl flow area formed by the first swirling flow forming means, characterized by being larger than the swirl flow area of the low-oxygen gas formed by the second swirling flow forming means.

According to the present invention, a vertical downward flow of fine carbide and air (hereinafter referred to as primary air) is formed from the burner in a vertical cylindrical furnace to prevent local damage to the furnace wall. can do.
Further, a low oxygen gas is introduced into the plane orthogonal to the vertically downward flow from the side wall together with air (hereinafter referred to as secondary air), and the outside is a low oxygen gas and the inside is secondary air. A first swirling flow is formed. Thereby, it can suppress that the ash which generate | occur | produces by combustion of a fine powder carbide and primary air, and floats on the flame flow flies to a ceiling direction or a side wall direction. Therefore, it is possible to suppress slag generation (ash adhesion), that is, slugging at the ceiling and side walls. In addition, the introduction position of the low oxygen gas and the secondary air is closer to the ceiling, that is, the introduction portion of the fine carbide and the primary air, and the effect of suppressing the slagging is greater, and it is preferable that the introduction position is close to the ceiling.
In addition, since the furnace has a vertical cylindrical shape, the swirling flow is less disturbed compared to a square-shaped furnace. Ash retention is suppressed.

  Further, since secondary air is swirled in the inner portion of the first swirl flow, the finely divided carbide is optimally subjected to secondary combustion in the inner portion of the first swirl flow to which the secondary air is supplied, Generated CO (unburned gas) is also reduced.

  Further, a swirl flow is generated so as to be orthogonal to a flame composed of combustion of fine carbide and primary air, and air is used on the inside to facilitate secondary combustion of the fine carbide, and further, low oxygen gas is provided on the outside. As a result, it is possible to suppress the flame temperature from significantly rising, and to suppress the generation of NOx. Furthermore, by making the furnace wall a fireproof structure, it is possible to operate with a load change without greatly reducing the outlet gas temperature even during low load operation.

  Furthermore, the flow of the vertically downward fine powder carbide and primary air, and the first swirl flow introduced by the configuration of the inner secondary air and the outer low oxygen gas, introduce the low oxygen gas on the subsequent stage side, and Mixing is promoted by forming a second swirling flow having a swirling area smaller than that of the first swirling flow, and the temperature is adjusted.

Further, the first swirl flow forming means blows the air and the low oxygen gas in a tangential direction of a first virtual circle in a plane orthogonal to the flow direction of the combustion gas in the furnace, and the first virtual flow A swirling flow along a circle is formed.
By blowing air from two or more outlets in the tangential direction of the first virtual circle in a plane orthogonal to the flow direction of the combustion gas in the furnace, the first along the first virtual circle A swirling flow can be generated very stably. For example, a swirl flow can be generated more stably by blowing air in a tangential direction of the first virtual circle from a plurality of places such as four places.

Further, the second swirl flow forming means blows the low oxygen gas in a tangential direction of the second virtual circle in a plane perpendicular to the flow direction of the combustion gas in the furnace, and the second virtual circle is injected into the second virtual circle. It is characterized by forming a swirl flow along.
The low oxygen gas is blown from the two or more outlets in the tangential direction of the second virtual circle in a plane orthogonal to the flow direction of the combustion gas in the furnace, so that the second oxygen gas along the second virtual circle 2 swirl flows can be generated very stably. For example, when the low oxygen gas is blown in the tangential direction of the second virtual circle from a plurality of places such as four places, the swirl flow can be generated more stably.

In the first swirl flow forming means, the inner tube and the outer tube are arranged concentrically, air is passed through the inner tube, and low oxygen gas is passed between the inner tube and the outer tube. It is a double tube nozzle that blows in the tangential direction of the first virtual circle.
Thereby, the 1st swirl | vortex flow which made the outer side low oxygen gas and the inner side secondary air can be formed easily.

The first swirling flow forming means includes a first outlet for blowing air in a tangential direction of the first virtual circle, and a second outlet for blowing low oxygen gas in a tangential direction of the first virtual circle. An outlet is provided so that the air blown from the first outlet is swirled closer to the center of the first virtual circle than the low oxygen gas blown from the first outlet. Features.
Thereby, the 1st swirl | vortex flow which made the outer side low oxygen gas and the inner side secondary air can be formed easily.

  Further, as a method invention for solving the problem, a fine carbide combustion method of burning a fine powder carbide and air by a burner provided at the furnace inlet to a furnace having a combustion region for burning fine powder carbide, From the upper part of the vertical cylindrical furnace, fine carbide and air are jetted vertically downward by the burner, and the low oxygen gas is placed on the outer periphery in a plane perpendicular to the combustion gas flow downstream of the burner. Air and low oxygen gas are blown so as to form a first swirling flow of air and low oxygen gas, and in a plane perpendicular to the combustion gas flow downstream of the first swirling flow. Further, low oxygen gas is blown so as to form a second swirl flow of low oxygen gas, and the first swirl flow area is made larger than the second swirl flow area.

  The air and the low oxygen gas are blown in a tangential direction of a first virtual circle in a plane orthogonal to a combustion gas flow direction, and the first swirl flow is formed along the first virtual circle. To do.

  The low oxygen gas is blown in a tangential direction of a second imaginary circle in a plane perpendicular to the flow direction of the combustion gas, and the second swirl flow is formed along the second imaginary circle. .

  As described above, according to the present invention, primary air and pulverized coal are ejected vertically downward into the furnace, thereby preventing local damage to the furnace wall and further suppressing the generation of slagging and NOx. In addition, it is possible to provide a pulverized carbide combustion apparatus and a method thereof that can operate with a load change without lowering the outlet gas temperature even during low load operation with a furnace wall as a fireproof structure.

It is a schematic block diagram of a carbide combustion apparatus. It is AA sectional drawing in FIG. It is BB sectional drawing in FIG. It is a whole block diagram of the cogeneration system of the carbonization furnace using the pulverized carbide combustion apparatus of the present invention. It is AA sectional drawing in FIG. 1, and shows another example.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.

  FIG. 4 is an overall configuration diagram of a cogeneration system for a carbonization furnace using the pulverized carbide combustion apparatus of the present invention. With reference to FIG. 4, the cogeneration system of the carbonization furnace which is an example using the pulverized carbide combustion apparatus of the present invention will be described.

  The system according to the present embodiment includes an asphalt production plant 170, a carbonization furnace 108 provided in the asphalt production plant 170, a gas combustion apparatus 1b for combusting pyrolysis gas from the carbonization furnace 108, and a fine powder carbide obtained by pulverizing the carbide. , A boiler 110 that recovers heat from high-temperature combustion gas, a power generation facility 122 that generates power using high-temperature steam generated in the boiler 110, a gas combustion apparatus 1b, and a pulverized carbide combustion apparatus 1 is mainly composed of an air preheater 172 that produces high-temperature air using a part of the combustion exhaust gas from No. 1. In this embodiment, the asphalt production plant 170 is provided as an example, but the present invention is not limited to this, and another hot air utilization facility may be provided.

The flow of this system will be described together with the specific configuration of each device.
The receiving supply facility 102 is supplied with an object to be pyrolyzed and gasified in the carbonization furnace 108. Examples of the object to be treated include biomass 130 such as plants, waste wood, agricultural waste, livestock manure, sewage sludge, and the like.
Biomass 130 supplied from the receiving supply facility 102 is conveyed on the input conveyor 104 and is quantitatively input from the screw feeder 106 into the carbonization furnace 108.
The carbonization furnace 108 is an externally heated rotary kiln that heats the inside of the furnace by indirect heating. The carbonization furnace 108 is a device in which a heating jacket is provided around the furnace and the biomass 130 in the carbonization furnace 108 is heated by circulating a high-temperature combustion gas 132 through the heating jacket. The externally heated rotary kiln can pyrolyze and gasify biomass with a small amount of fly ash generated. In addition, since it is an indirect heating type, the oxygen concentration inside the kiln where the biomass stays can be kept at a very low value and uniform heating is possible, so that a high-calorie and uniform carbide 136 is produced. Can do.

The pyrolysis gas 134 generated by carbonization in the carbonization furnace 108 is guided to the gas combustion device 1b. In the gas combustion apparatus 1b, the pyrolysis gas 134 is burned while supplying the combustion air 138, and the high-temperature combustion gas 132 is generated.
At the same time, the carbide 136 produced in the carbonization furnace 108 is separated and removed from foreign matters such as metal by a foreign matter separation device (not shown), and is pulverized by a pulverizer (not shown) to become fine powder carbide. As in the gas combustion apparatus 1b, the carbide 136 is burned while supplying the combustion air 138, and a high-temperature combustion gas 132 is generated. The auxiliary fuel 140 can also be used when the combustion chamber is heated.
In this embodiment, the pyrolysis gas 134 and the carbide 136 generated in the carbonization furnace 108 are combusted in the separate combustion devices 1b and 1. However, the present invention is not limited to this. In this combustion chamber, the pyrolysis gas 134 and the carbide 136 may be combusted to generate the high-temperature combustion gas 132.

A part of the high-temperature combustion gas 132 generated in this way is supplied to the heating jacket of the carbonization furnace 108 and used for indirect heating of the carbonization furnace 108. At least a part of the other high-temperature combustion gas 132 is supplied to the boiler 110, and the boiler 110 generates high-temperature steam 144 using the sensible heat of the high-temperature combustion gas 132. The generated high-temperature steam 144 is guided to the power generation facility 122 provided in the boiler 110 and used for power generation. The electric power generated here may be supplied to the other as well as the necessary power for operation of the asphalt production plant 170.
Moreover, a part of high-temperature steam produced | generated with the boiler 110 can also be supplied to the carbide | carbonized_material 136 produced | generated with the carbonization furnace 108, In this case, it is used for prevention of a fine particle scattering or cooling.

  Part of the exhaust gas 148 after heat recovery in the boiler 110 is introduced into the temperature reducing tower 114 and cooled by spraying the cooling water 154. The cooled exhaust gas 156 is introduced into the bag filter 116, and acid gases such as SOx and HCl are neutralized by the supply of slaked lime 158, and further introduced into the bag filter 116 to remove dust. Fly ash 146 collected by the boiler 110, the heater 112, the temperature reducing tower 114, and the bag filter 116 is processed by a fly ash treatment facility (not shown).

The exhaust gas discharged from the bag filter 116 is dehumidified and reduced in temperature by the smoke-washing tower 124, and SO _x , HCl and the like are further removed by caustic soda. The cleaned exhaust gas 160 is heated by the heater 112, then NOx is removed by supplying ammonia 162 in the denitration reactor 118, and discharged from the chimney 120 to the atmosphere. A part of the boiler outlet exhaust gas 148 is supplied to the carbide combustion device 1 and the gas combustion device 1b.
Note that the smoke washing tower 124, the denitration reaction tower 118, and the heater 112 may be omitted depending on the properties of the exhaust gas, and these apparatus configurations can be selected as appropriate.

  On the other hand, at least a part of the high-temperature combustion gas 132 generated by the gas combustion device 1 b and the carbide combustion device 1 is supplied to the air preheater 172. In the air preheater 172, the air 178 and the high-temperature combustion gas 174 are heat-exchanged to generate high-temperature air 176. The combustion gas reduced in temperature by heat exchange is sent to the rear stage side of the heater 112 and processed together with other exhaust gas 148.

  The clean high temperature air 176 generated by the air preheater 172 is supplied to the asphalt manufacturing plant 170 and supplied to a dryer or the like at the plant. In the asphalt production plant 170, fuel such as aggregate, air, and kerosene is supplied to produce asphalt products such as asphalt composites. Here, by using high-temperature air 176, the fuel in the asphalt production plant is reduced. It becomes possible to do. Moreover, since the high-temperature air 176 is clean air generated by exchanging the air 178 in the air preheater 172 while using the heat source of the carbonization furnace 108, impurities are mixed into the manufactured asphalt product. No high quality products can be manufactured.

  In the cogeneration system of the carbonization furnace described with reference to FIG. 4 as described above, the fine powder combustion apparatus of the present invention is used as the carbide combustion apparatus 1. FIG. 1 is a schematic configuration diagram of the carbide combustion apparatus 1, FIG. 2 is a cross-sectional view taken along line AA in FIG. 1, and FIG. 3 is a cross-sectional view taken along line BB in FIG. The carbide combustion apparatus 1 of the present invention has a vertical cylindrical shape, and the inside is covered with a refractory material.

  The fine carbide combustion apparatus 1 includes a powder burner 10 on the ceiling, a double pipe nozzle 4 which will be described later on a side wall surface immediately below the powder burner 10, and below the double pipe nozzle 4. The low oxygen gas injection nozzles 6 and 8 are provided in two steps on the side wall surface. In this embodiment, the low oxygen gas injection nozzles 6 and 8 are provided in two stages, but one or three or more stages may be provided. Further, an ash extraction port 7 is provided at the bottom, and an exhaust gas outlet 14 is provided on the lower side wall surface of the low oxygen gas injection nozzle 8. In addition, observation windows 16 are provided at various places.

  Next, operation | movement of the carbide | carbonized_material combustion apparatus 1 of this invention is demonstrated. First, pulverized carbide obtained by pulverizing the carbide 136 produced in the carbonization furnace 108 with a pulverizer (not shown) is conveyed in the vapor phase to the carbide combustion apparatus 1 and is combusted air (hereinafter referred to as primary) from the powder burner 10. (Referred to as air) 138 and supplied to the furnace 2 constituting the carbide combustion apparatus 1. The pulverized carbide supplied into the furnace 2 together with the primary air burns in the furnace 2 while creating a vertically downward combustion gas flow.

  At this time, air (hereinafter referred to as secondary air) and low oxygen gas are introduced into the furnace 2 from the double tube nozzle 4 provided below the powder burner 10 and on the side wall surface of the furnace nearest to the powder burner 10. . Although the low oxygen gas may be introduced from the outside, a part of the boiler 110 outlet exhaust gas 148 is used as the low oxygen gas.

As shown in FIG. 2, four double tube nozzles 4 (4a, 4b, 4c, 4d) are provided. In the double tube nozzle 4a, virtual circles of the inner tube 44a and the outer tube 42a are arranged concentrically. Secondary air is introduced into the inner tube 44a, and the inner tube 44a and the outer tube 42a In the meantime, a part of the exhaust gas 148 is introduced through the introduction passage 46a. The double tubes 4b, 4c, and 4d have the same configuration as the double tube 4a.
The secondary air and exhaust gas introduced into each double tube nozzle 4a, 4b, 4c, 4d are orthogonal to the direction of combustion gas flow in the furnace 2 from each double tube nozzle 4a, 4b, 4c, 4d. A surface is blown in the tangential direction of the first virtual circle 40 on the horizontal plane. The air and exhaust gas blown into the furnace 2 from the double tube nozzles 4a, 4b, 4c, and 4d are exhaust gas inside the furnace 2 along the first virtual circle 40 (furnace inner wall side) and exhaust gas inside (first The center side of one virtual circle 40) forms a swirling flow with a secondary air configuration.

  Due to the swirl flow formed by the secondary air and exhaust gas blown from the double pipe nozzles 4a, 4b, 4c, and 4d, the incineration fly ash generated by the combustion of the primary air and the fine powdered carbide causes the flame to rise. It is possible to prevent scattering and adhering to the ceiling surface and the side wall.

  Further, the double tube nozzles 4a, 4b, 4c and 4d form a swirling flow with the exhaust gas on the outside and the secondary air on the inside, so that the powder burner 10 is combusted by the supply of the inner secondary air. In addition, the introduction of the exhaust gas to the outside can slow the combustion and prevent a rapid temperature rise of the gas in the furnace, thereby suppressing the generation of NOx.

That is, by using a double pipe nozzle to form a swirling flow with exhaust gas on the outside and secondary air on the inside, the temperature rise of the inner combustion wall is suppressed by suppressing the temperature rise of the primary combustion field, which is the highest temperature. In addition, it is possible to suppress slagging, and by supplying exhaust gas and secondary air in a swirling flow from a direction perpendicular to the burner flame in the immediate vicinity of the vertically downward powder burner, Ash scattering can be reduced, and NOx generation can also be suppressed by slow combustion.
In order to exhibit such an effect efficiently, it is good to make the area of the said swirl flow into about 30 to 60% with respect to a furnace cross-sectional area.

  In this embodiment, the double pipe nozzle 4 is used to form a swirling flow of the secondary air and the exhaust gas. However, the nozzle shape swirls with a configuration in which the outside is the exhaust gas and the inside is the secondary air. If the flow can be formed, it is not limited to the double tube nozzle. For example, instead of the double tube nozzles 4a, 4b, 4c, 4d as shown in FIG. 5, the outlets 5a, 5b, 5c, 5d can be provided. The outflow port 5a is formed with two flow channels 52a and 54a having a rectangular cross section, and secondary air flows into the flow channel 54a whose extension line is close to the center of the first virtual circle 40. A part of the exhaust gas 148 is introduced into the flow path 54a that is introduced and whose extension line is close to the furnace wall. The exhaust gas and the secondary air introduced into the flow paths 52a and 54a having a rectangular cross section are blown in the tangential direction of the first virtual circle 40, and outside the furnace 2 along the first virtual circle 40 (furnace A swirling flow is formed with a configuration in which the inner wall side is exhaust gas and the inner side (center side of the first virtual circle 40) is secondary air.

  Further, low oxygen gas is introduced into the furnace from low oxygen gas introduction nozzles 6 and 8 provided on the side wall surface of the furnace below the double tube nozzles 4a, 4b, 4c and 4d. Since the low oxygen gas injection nozzles 6 and 8 have the same structure and configuration, only the case where a low oxygen gas swirl flow is formed in the low oxygen gas injection nozzle 6 will be described here. As shown in FIG. 3, four low oxygen gas injection nozzles 6 (6a, 6b, 6c, 6d) are provided, and the combustion gas in the furnace is supplied from each of the low oxygen gas injection nozzles 6a, 6b, 6c, 6d. Low oxygen gas is blown in the direction perpendicular to the flow, that is, in the tangential direction of the second virtual circle 60 in the horizontal plane. The low oxygen gas blown from the low oxygen gas injection nozzles 6a, 6b, 6c, and 6d uses a part of the exhaust gas 148 like the low oxygen gas blown from the double tube nozzles 4a, 4b, 4c, and 4d. . The exhaust gas blown into the furnace 2 from the low oxygen gas injection nozzles 6 a, 6 b, 6 c, 6 d forms a swirling flow along the second virtual circle 60 in the furnace 2. The area of the second virtual circle 60 is not particularly limited as long as it is smaller than the area of the first virtual circle 40. Further, the temperature of the low oxygen gas blown into the furnace 2 from the low oxygen gas injection nozzles 6a, 6b, 6c, 6d is not particularly limited, but the temperature of the combustion gas is effectively reduced without impeding the combustion of the finely divided carbide. Therefore, it is preferable to set it as about 200-300 degreeC.

  By blowing low oxygen gas from the low oxygen nozzles 6a, 6b, 6c and 6d, the low oxygen gas is mixed with the combustion gas in the furnace, and the inner wall temperature of the furnace is lowered to effectively suppress slagging and gas. Generation of NOx is suppressed by suppressing a local rise in temperature.

  In this way, the combustion gas burned in the fine carbide combustion apparatus 1 is sent from the gas outlet 14 to the boiler 108 or the like for use.

  Further, an ash extraction outlet 12 is provided at the lowermost part of the furnace 2 so that ash accumulated at the bottom of the furnace 2 can be extracted from the ash extraction outlet 12 as appropriate.

  By using the carbide combustion apparatus 1 of the present invention, the furnace 2 and the boiler 110 can be individually installed. Therefore, the load can be changed in one furnace configuration, and high-temperature air can be produced simultaneously with steam production. Therefore, in FIG. 4, when both the power generation facility 122 and the asphalt production plant 170 are operated, a high load operation is performed. When the power generation facility 122 is operated and the asphalt production plant 170 is stopped, a low load operation is performed, and the requirements of the subsequent facilities are met. The load can be changed accordingly.

  In the present embodiment, the carbonization furnace 108, the carbide combustion device 1 and the gas combustion device 1b are provided one by one. For example, a plurality of the carbonization furnace and the corresponding carbide combustion device and gas combustion device are provided in parallel. By introducing combustion gas generated in the plurality of fine carbide combustion devices and gas combustion devices into one boiler, heat recovery from the plurality of gas combustion devices can be achieved at a low equipment installation cost.

  The furnace wall is fireproof and the outlet gas temperature does not decrease during low-load operation. Therefore, operation with load changes is possible, and primary air and pulverized coal are jetted vertically downward into the furnace. Thus, it is possible to provide a pulverized carbide combustion apparatus and method that can prevent local damage to the furnace wall and further suppress the generation of slagging and NOx.

DESCRIPTION OF SYMBOLS 1 Carbide combustion apparatus 1b Gas combustion apparatus 4, 4a, 4b, 4c, 4d Double pipe nozzle 6, 8 Low oxygen gas injection nozzle 42a, 42b, 42c, 42d Outer pipe 44a, 44b, 44c, 44d Inner pipe 40 1st Virtual circle 60 Second virtual circle 108 Carbonization furnace 110 Boiler 136 Carbide 148 Exhaust gas (low oxygen gas)

Claims (8)

In a furnace having a combustion region for burning fine powder carbide, and a burner for injecting and burning fine powder carbide and air in the furnace, the burner provided in the furnace inlet portion,
The furnace is in a vertical cylindrical shape, and the burner is provided in the furnace ceiling, and is arranged so that the fine carbide and air are jetted vertically and burned,
Along with the combustion gas flow in the furnace, air and low oxygen gas are blown into the furnace downstream of the burner to form a swirl flow in which the low oxygen gas is positioned on the outer periphery in a plane perpendicular to the flow of the combustion gas. First swirl flow forming means, and second swirl flow for forming a swirl flow in a plane orthogonal to the flow of the combustion gas by blowing low oxygen gas into the furnace downstream of the first swirl flow forming means Forming means,
The fine carbide combustion apparatus characterized in that the swirl flow area formed by the first swirl flow forming means is larger than the swirl flow area of the low oxygen gas formed by the second swirl flow forming means. .   The first swirl flow forming means blows the air and the low oxygen gas in a tangential direction of a first virtual circle in a plane perpendicular to the flow direction of the combustion gas in the furnace, and into the first virtual circle 2. A pulverized carbide combustion apparatus according to claim 1, wherein a swirling flow is formed.   The second swirl flow forming means blows the low oxygen gas in a tangential direction of a second virtual circle in a plane perpendicular to the flow direction of the combustion gas in the furnace, and follows the second virtual circle 3. A pulverized carbide combustion apparatus according to claim 2, wherein a swirl flow is formed.   In the first swirl flow forming means, an inner tube and an outer tube are concentrically arranged, air is passed through the inner tube, and low oxygen gas is passed between the inner tube and the outer tube, and these are passed through the first tube. The fine-powder carbide combustion apparatus according to claim 2 or 3, wherein the fine-powder carbide combustion apparatus is a double pipe nozzle that blows in a tangential direction of one virtual circle.   The first swirl flow forming means includes a first outlet for blowing air in a tangential direction of the first virtual circle, and a second outlet for blowing low oxygen gas in a tangential direction of the first virtual circle. Are arranged so that air blown from the first outlet is swirled closer to the center of the first virtual circle than the low oxygen gas blown from the first outlet. The pulverized carbide combustion apparatus according to claim 2 or 3. In a fine carbide combustion method of burning fine powder carbide and air into a furnace having a combustion region for burning fine powder carbide by a burner provided at the furnace inlet,
From the upper part of the vertical cylindrical furnace, fine carbide and air are jetted vertically downward by the burner,
Air and low oxygen gas so that the low oxygen gas forms a first swirling flow of the low oxygen gas and the air located on the outer periphery in a plane orthogonal to the flow of the combustion gas downstream of the burner gas flow from the burner Infuse,
Low oxygen gas is blown in a plane perpendicular to the combustion gas flow downstream of the first swirl flow to form a second swirl flow of low oxygen gas,
The fine carbide combustion method, wherein the first swirl flow area is larger than the second swirl flow area.   The air and the low oxygen gas are blown in a tangential direction of a first virtual circle in a plane orthogonal to a combustion gas flow direction, and the first swirl flow is formed along the first virtual circle. The method for combusting fine powder carbide according to claim 6.   The low oxygen gas is blown in a tangential direction of a second imaginary circle in a plane perpendicular to the flow direction of the combustion gas, and the second swirl flow is formed along the second imaginary circle. The method for combusting fine carbide according to claim 7.

Images